1. Field of the Invention
The present invention relates to a system and a method for positioning a base station for a mobile communication network, and more particularly, to a system and a method for positioning a base station for a mobile communication network using CDMA, in consideration of interference caused by adjacent base stations.
2. Prior Art
It is necessary to verify whether or not a base station is suited for the site when the base station for communicating with a mobile station (terminal) is installed in a mobile communication network.
There has been used a continuous wave transmitter and receiver for positioning the base station in the past.
It is necessary to install a new base station when shadow area exists between the converges of existing base stations. In this case, the continuous wave transmitter is installed on a candidate base station, in such a manner that it generates the continuous wave continuously having frequency which hasn""t been broadcasted from adjacent base stations. Meanwhile, under the circumstances, the continuous wave receiver being carried by a vehicle measures, RSSI (Received Signal Strength Indication) of the continuous wave while a vehicle loading a continuous wave receiver is running around the continuous wave transmitter, in order to determine the position of the new base station.
At this time, judging a position at which the RSSI is equal to xe2x88x9280 dBm as a coverage boundary of the base station (capable of changing according to a criterion), the new base station is determined in consideration of the overlapping portion of a new coverage and the existent coverage.
In the above description, Ec/It (Accumulated pilot energy ratio during a PN chip period with respect to a maximum spectrum density in a receiving band) is estimated at xe2x88x9215 db (a minimum value for communicating). However, since the Ec/It may become less than xe2x88x9215 db due to the interference of the adjacent base station actually, there are problems in determining the position of the base station according to the conventional art. Here, Ec/It=Ec/(Io+Ioc+Now), and Ec is an accumulated pilot energy during a PN chip period, It is total interference, Io is interference of a corresponding cell, loc is interference of an adjacent cell, and NoW is thermal noise existing in a natural world. In the present description, the Ec/It is expressed to Ec/Io for the convenience of illustration.
The present invention has been proposed to overcome the above-described problems in the prior art, and accordingly it is the object of the present invention to provide a system for positioning a base station for mobile communication network, capable of positioning a base station properly by simultaneously measuring a continuous wave signal and a common frequency signal gathering from an adjacent base station with regard to a circumferential interference under actual circumstances.
It is another object of the present invention to provide a method for positioning a base station by using the system for positioning a base station.
To achieve the above object, the present invention provides a system for positioning a base station used for a mobile communication system using CDMA, comprising: a plurality of continuous wave generators for generating continuous waves of constant output power, the continuous waves having frequencies different from each other; a continuous wave receiver for receiving the continuous waves from the plural of continuous wave generators so as to measure RSSI of the continuous waves, and receiving G.P.S. information at the same time; and a computer for receiving the RSSI of the continuous waves and the G.P.S. information so as to measure Ec/Io of a predetermined site.
The continuous wave generator comprises: a key pad for selecting an output frequency and an output power; a microprocessor for receiving an input of the key pad so as to control the output frequency and the output power, the microprocessor for making a command to display the values of the output frequency and the output power, a frequency synthesizer for receiving the command from the microprocessor to output a selected frequency; an output power regulator for receiving the command from the microprocessor to control an output power of the selected frequency; a high-output amplifier for amplifying a signal from the output power regulator; and a transmitting antenna for broadcasting an output of the high-output amplifier.
The continuous wave receiver comprises: a receiving antenna for receiving the continuous waves; a frequency generator for periodically generating a plurality of frequencies different from each other; a frequency synthesizer for synthesizing an output frequency of the frequency generator and a signal received on the receiving antenna so as to convert into an intermediate frequency; a switching part for outputting a predetermined signal by periodically switching the intermediate frequency from the frequency synthesizer; a RSSI sensor for sensing the RSSI from an output of the switching part; an A/D converter for converting the RSSI into a digital signal; a decoder for receiving the digital signal of the RSSI while controlling the output frequency from the frequency generator and a switching operation of the switching part; a G.P.S. antenna for receiving G.P.S. signal; and a G.P.S. receiver for measuring latitude, longitude and time information from the G.P.S. signal.
Meanwhile, a method for positioning a base station used for a mobile communication system using CDMA, comprising the steps of: generating continuous waves having a constant output power and frequencies different from each other, by using a plurality of continuous wave generators; receiving the continuous wave from the plural of continuous wave generators so as to measure RSSI of the continuous waves, and receiving GSP information at the same time; and measuring Ec/Io of a predetermined site from the RSSI of the continuous waves and the G.P.S. Information.
In the step of measuring the RSSI of the continuous wave, and at the same time, receiving the G.P.S. information by using the continuous wave receiver, the frequency of adjacent common base station is also received so as to measure RSSI thereof.